Just received a "Trade-A-Plane" large magazine/newspaper item in my mail today, and despite being mostly a US-based operation, they seem to have the occasional overseas advertisement in there.
Noticed that this was being sold on page 58:
"Historic aeroplane. World's first business aircraft. Orig. owner Sir Philip Sassoon, Secretary of State for Air, Commander of 601 Sqdn. (Billy Fiske's Sqdn.). Owned by Queen's Uncle during WW2. Queen Mother flew in it illegally. Only 190 hrs s/rebuild. Priceless, $1.98M, open to offer."